ÄKTAmicro

• Inspect the complete system for eluent leakage.
• The system can be left filled with buffer overnight. If you are not using the separation unit for a few days, wash the flow path with distilled water. Replace the column by a bypass capillary. Then wash the system with 20% ethanol and store it in 20% ethanol. Make sure that all tubing and all flow paths used are rinsed.

• Check for leakage. If there is a sign of liquid leaking between the pump head and the housing side panel or increased or decreased volume of rinsing solution, replace the pumphead.
• When changing eluent, it is important to remove trapped air. Run the Purge the pump procedure below. If there is still air in the inlet tubing, stop and run the Removing trapped air bubbles from the pump procedure below.

Check the inlet filters visually and replace them if necessary.

Replace the on-line filter.

• Change rinsing solution. Always use 20% ethanol as rinsing solution.
• If the volume of rinsing solution in the storage bottle has increased, it can be an indication of internal pump leakage. Replace the pumphead.
• If the volume of rinsing solution in the storage bottle has decreased significantly, check if the rinsing system connectors are mounted properly.
• If the rinsing system connectors are not leaking, the rinsing membranes or piston seals may be leaking. Replace the pumphead.

Run the Cleaning the system procedure.

Run the Checking the instrument procedure below.

Run the Cleaning the flow cell and optical fiber connectors procedure below.

Run the Cleaninging the conductivity flow cell procedure below. Cleaning the flow cell may be required more often if crude samples are regularly used.

Check that the mixer chamber is clean and without damage. Check the tubing connectors. Replace if required.

Check for external and/or internal leakage. Run the Changing channel plate and distribution plate procedure below yearly or when required.

Replace the complete mixing chamber on a regular basis.

Replace the pumphead.

Run the Cleaninging the conductivity flow cell procedure below. Cleaning the flow cell may be required more often if crude samples are regularly used.

1
Fill a reservoir flask with distilled water. Immerse the inlet tubings of both pump modules, with filters, in the water.

Note: Never place the reservoir flask below the level of the pump inlet.

2
Connect a male Luer syringe of about 30 ml to the open end of the purge tubing.

3
Connect the male Luer connector at the other end of the purge tubing to the left purge valve at pump module module A.

4
Turn the purge valve counterclockwise half a turn to open it and slowly draw eluent to the syringe.

5
When fluid starts to enter the syringe continue to draw a few milliliters before closing the purge valve. Check that there is no air left in the inlet tubing.

6
Repeat steps 3 to 5 for pump module B, if fitted.

During routine operation, the presence of air bubbles in the pump heads is seen as an erratic flow, a noisy detector signal or an irregular pressure recording. With air bubbles trapped in the pump, the pressure reading on the display will fluctuate considerably.

To remove the air from the pump:

1.
If the air has accumulated because of a leaking connector, correct the fault.

2.
Ensure that the inlet filter is fully immersed in eluent.

3.
Run the Purge the pump procedure.

If the problem remains, try to remove the air bubbles in accordance with the method described below. Use 100% methanol.

1.
Run at 2 ml/min.

2.
Continue to run for 10 minutes, or until the air bubble is removed.

3.
Run the Changing eluent procedure.

When changing from one eluent to another, it is extremely important that the two eluents are totally miscible with one another. If the two eluents are immiscible, the pump should be flushed first with an intermediate liquid, which is miscible with both eluents. Failure to do this will cause a wrong flow of eluent from the pump.

When changing from a salt-containing buffer to an organic solvent, use water as the intermediate liquid to prevent precipitation.

1
Stop the pump by setting it in End mode.

2
Transfer the inlet tubing into the new eluent or into the intermediate liquid.

3
Run the pump at a flow rate and time as specified in the table.

4
Stop the pump. If an intermediate liquid is being used, transfer the inlet tubing into the final eluent and repeat step 3 with the new eluent.

In UNICORN, select instruction PumpWash in System Control:Manual:Pump.

Clean the flow path every month or when problems such as ghost peaks occur.

1
Disconnect the column and replace it with the G4 tubing.

2
Place all the inlet tubing in 100% acetonitrile.

3
Manually, perform PumpWash for all the four inlet tubings.

4
Flush the whole system with 100% acetonitrile for 5 minutes (1 ml/min).

5
Immediately, repeat step 3 and 4 with distilled water to rinse the flow path from acetonitrile.

1
Select menu Check, press OK.

2
Select menu Check Lamp Intensity.

Check lamp Intensity
210nm 85%
300nm 95%

If the lamp intensity is < 20%, contact your local GE Healthcare service representative for lamp replacement or change of internal optical fiber.

1
Select menu Check, press OK.

2
Select menu Check Lamp Run Time.

Check Lamp Run Time 200h

If the lamp on time is > 4000 hours, contact your local GE Healthcare service representative for lamp replacement.

The flip time is the time the monochromator stepper motor has been in operation.

1
Select menu Check, press OK.

2
Select menu Check Flip Time.

Check Flip Time 50h

If the flip time is > 2000 hours, contact your local GE Healthcare service representative for maintenance.

Cleaning the flow cell

A clean flow cell and optical connectors are essential for ensuring the correct operation of the UV-monitor.

1
Connect a syringe to the inlet of the flow cell and squirt distilled water through the cell in small amounts. Then fill the syringe with a 10% surface active detergent solution like Decon 90, Deconex 11, RBS 25 or equivalent, and squirt five times.

2
After five squirts, leave the detergent solution in the flow cell for at least 20 minutes.

3
Pump the remaining detergent solution through the flow cell.

4
Rinse the syringe and flush the cell with distilled water (10 ml).

Cleaning the optical fiber connectors

Wipe with 30% isopropanol on lens paper.

Instrument housing

Wipe the instrument housing regularly with a damp cloth. Let the instrument dry completely before use.

If the conductivity measurements are not comparable to previous results, the electrodes in the flow cell may be contaminated and require cleaning.

To clean the flow cell:

1
Pump 15 ml of 1 M NaOH at 1 ml/min through the flow cell either by using a pump or a syringe.

2
Leave it for 15 minutes.

3
Rinse thoroughly with 50 ml de-ionised water.

Note: If the flow cell is totally blocked, the blockage can be broken using a thin needle or a piece of string with a diameter less than 0.3 mm.

A replacement kit, Valve Kit INV-907, is available, see Spare parts recommended to keep on site in the Spare Parts section under the Related Products tab for code no.

1
Ensure that the valve is in position 1 and then disconnect it from the pump.

2
Remove the 4 screws on the front using the supplied 3 mm Allen key. Loosen each one equally in turn so the distribution plate comes off parallel to the valve body.

3
Slide the screws out.

4
Remove the distribution plate containing the ports.

5
Remove the old channel plate and insert a new one.

6
Remount a new distribution plate so that the text 3 is horizontal and to the right of the central tubing connection. Using the Allen key, tighten the 4 screws in turn, a little at a time, until the distribution plate is fixed to the valve body.

If there are signs of liquid leaking between the pump head and the housing side panel or the volume of the rinsing solution has increased or decreased, replace the piston seal of the leaking pump head.

CAUTION! Do not disassemble the pump head unless there is good reason to believe that the seal is leaking. Always ensure that sufficient spare components are available before attempting to replace the piston seal. It is not possible to reinstall a used piston seal after removal.

Note: The power must be switched OFF when removing and refitting the pump heads.

Note: Always replace the piston seals on both pump heads at the same time. An even better practice is to replace all four piston seals.

Spare parts and tools required:
Seal kit containing:
2 or 4 piston seals
2 or 4 rinse membranes
1/4 inch wrench (supplied with the pump)
3 mm allen key (supplied with the pump)
Screwdriver (supplied with the pump)

Note: After a new seal has been installed, the pump should be run in. Run the Running-in a new piston seal procedure.

Note: Before disassembling the pump heads move all input buffers bottles below the level of the pump heads to prevent siphoning.

CAUTION! Read the following instructions carefully. The individual parts of the pump head can be assembled incorrectly. Take care to ensure that the orientation of each part is correct before continuing with the next instruction.

1
Switch off the pump at the mains power switch on the back panel.

2
Remove the piston seal rinsing system. The connectors are simple plugin fittings.

3
Completely loosen the tubing connector on the outlet valve.

4
Remove the Switch valves and disconnect the tubing. Unscrew the two white knurled screws under the pump to release the support bracket locking the inlet manifold into the inlet valve. Gently lower and remove the complete manifold.

5
Using the Allen key, unscrew and completely remove one of the two Allen screws locking the pump head in position.

6
When unscrewing the second locking screw, push firmly on the front face of the pump head to compensate for the pressure of the piston return spring. Hold the pump head firmly to prevent it from twisting. Remove the second screw and, without allowing the pump head to twist sideways, carefully pull it out.

7
Place the pump head face down on the bench. Pull out the piston together with the return spring.

8
Inspect the piston and return spring for sign of damage. If damaged, they should be replaced.

9
Wipe the piston with a clean cloth. If salt solutions have been used the piston may be slightly corroded. This corrosion can be removed with a rubber eraser. If it cannot be wiped or rubbed clean, scrape off any deposits with a scalpel or razor blade. Inspect the piston with a magnifying glass for scratches. Replace with a new piston if any scratches or cracks are found.

10
Remove the two screws securing the drain plate and the rinse chamber. Remove and discard the rinsing membrane. Remove the rinse chamber. Remove also the support washer.

11
Gently withdraw the piston seal. Discard the used seal.

12
The pump head, rinse chamber and drain plate should be carefully rinsed or cleaned in an ultrasonic bath, if available. If dirt can be seen on any surfaces, the inlet and outlet check valves should be removed and cleaned separately. Run the Cleaning the inlet and outlet check valves procedure.

13
Wet the new seal slightly and place it in the hole on the pump head and press it down into position with a hard flat object. Refit the support washer on top of the new seal.

14
With the pump head still facing downwards on the bench, place the rinse chamber onto the head with the rinse ports in line with the inlet and outlet check-valves. The conical depression in the rinse chamber should be facing upwards, ready to accept the new rinsing membrane. Fit the rinsing membrane with the conical face downwards.

15
Place the drain plate on top of the assembly. Use the two screws to lock the complete assembly together.

Note: Align the drainage hole in the drainage plate with the inlet check valve (the opposite side of the pump head marked OUT/UP).

16
Wipe clean the piston and remove all finger prints. Wet the piston and then insert it into the return spring. With the pump head facing downwards on the bench, insert the piston into the pump head by pushing it gently but firmly vertically downwards into the seal.

CAUTION! Do not push the piston at an angle to the head and DO NOT twist the piston.

17
Turn the head so that the inlet valve and drainage hole are facing downwards and the text UP/OUT on the pump head is facing upwards. Mount the complete pump head over the locating pins on the front panel. Locate the metal end of the piston and the spring towards the drive cam.

Hold the pump head firmly against the side panel of the housing with one hand. Do not allow the assembly to twist under pressure from the return spring. Using the Allen key, fit and tighten one of the Allen screws.

Fit and tighten the remaining Allen screw.

18
Reconnect the outlet tubing to the outlet check valve and the manifold block as described above.

19
Reconnect the inlet manifold and, if used, the switch valves.

20
Refit the tubing of the piston seal rinse system.

21
The pump should now be purged and the new piston seal carefully run the Running-in a new piston seal procedure.

The piston seal should be run-in using 100% methanol.

1
Ensure that the reservoir is filled with sufficient eluent. Immerse the inlet tubing in the eluent. The reservoir should be placed at least 30 cm above the pump inlet.

2
Connect a male Luer syringe of about 30 ml to the open end of the purge tubing.

3
Connect the male Luer connector at the other end of the purge tubing to the left purge valve at pump module module A.

4
Turn the purge valve counter-clockwise half a turn to open it and slowly draw eluent to the syringe.

5
When fluid starts to enter the syringe continue to draw a few milliliters before closing the purge valve. Check that there is no air left in the inlet tubing.

6
Repeat steps 3 to 5 for pump module B, if fitted.

7
Check that the outlet tubings are not blocked.

8
Connect a thin capillary or a column that will give sufficient back pressure.

9
Run the pump at 1 ml/min (or 2 ml/min at 50%B) at a back-pressure of 5-10 MPa for 2 hours, or longer if possible (e.g. overnight).

10
Finally, Change the eluent according to the procedure given below.

Typical symptoms of a damaged piston are observed as excessive piston seal wear, unstable pressure, a reduction in the flow or, in som cases, noise as the piston moves. The piston should be removed, examined for damage or salt precipitation and the replaced with a new piston if necessary.

If a damaged piston has been in operation, the piston seal will be destroyed and should be replaced. Run the Replacing the piston seal, membranes and piston procedure.

Spare parts and tools required:

• Seal kit
• 1/4 inch wrench
• 3 mm Allen key
• Screwdriver
• Piston kit

Faulty operation of the check valves is usually indicated by irregular flow, very low flow or unstable pressure traces. Probable causes of this are air or dirt in a check valve preventing it from closing to seal and hold the pressure.

Record the pressure according to instructions, checking the pump pressure at the end of this document and identify the faulty check valve by observing which pump head is delivering the flow according to check menu at the end of this document.

Try to clean the check valves in–place on the pump head by pumping distilled water at 2 ml/min for 2 minutes. This also prevents precipitation of crystals. The pump 100% methanol for approximately 10 minutes. If this does not correct the problem, follow the instructions for removing and then cleaning the valves.

Note: Change solvent to distilled water and flush out all salt before removing the check valves.

Tools required: A 13 mm, a 18 mm and a 1/4 inch wrench.

Before removing the check valves, move all input buffers bottles below the level of the pump heads, to prevent siphoning.

1
If the condition of the check valve is not improved by in–place cleaning, disconnect and remove the inlet manifold and outlet tubing.

2
Use the 13 mm wrench (inlet check valve) or the 18 mm wrench (outlet check valves) to remove the valve from the pump head.

3
Immerse the complete valve in methanol and place in an ultrasonic bath for some minutes.

Then repeat the ultrasonic bath with distilled water.

4
Refit the check valves. The inlet check valve (with a lip for the manifold and a larger diameter opening) is fitted to the side marked IN of the pump head. Tighten the valves until fully finger-tight and then use the wrench to tighten a further 1/3rd (110^o) of a turn. Do not overtighten the valves since damage to the internal components can occur.

5
Refit the outlet tubing and the inlet manifold.

6
Purge the pump carefully and check that the pumping action has been corrected.

Note: Check valves have precision matched components and should only be disassembled further by a trained service engineer. If the problem cannot be corrected, the valve should be replaced completely.

To check the pump function, a recording of the pressure can be made or by checking the pressure in UNICORN. This pressure recording is more sensitive than the reading on the display. By observing the piston stroke indicator in the Check menu together with the pressure trace, the pump head which is functioning abnormally can be identified.

There can be several causes of an abnormal pressure recording, for example:

• air trapped in the pump heads
• partially blocked solvent filters
• leaking connections
• piston seal leakage
• check valve malfunction
• piston damaged

Check menu

To enable trouble shooting it is possible to check which pump module head that delivers flow.

1
Select main menu Check, press OK.

2
The display shows the status of the pistons for both pump modules.

A: Left means that the left pump head is delivering flow in the A pump and

B: Right means that the right pump head in delivering flow in the B pump. At the changing point both are displayed. The A pump is closest to the front panel.

Note: 
Check Heads 2.30MPa
A: Left
B: Right

1
Select main menu Check, press OK.

2
Select sub menu Check Total Run Time. The display shows the accumulated operation time (Run and Hold mode) for the A and B pumps.

Note:
Check Total Run Time
A: 50 h
B: 20 h

1
Select main menu Check, press OK.

2
Select sub menu Check Piston Strokes. The display shows the accumulated number of piston strokes for the A and B pumps.

Note:
Check Piston Strokes
11374, 2398

1
Ensure that the pump is at zero pressure.

2
Select main menu Check, press OK.

3
Select sub menu Calib Press Offset, press OK. “Working, please wait ...” is displayed until the calibration is completed.

Service information relevant to the instrument can be checked. Information may not be available in all menus.

1
Select main menu Check, press OK.

2
Select sub menu Check Service Mode, press OK.

3
The service telephone number is displayed¹. Turn the selection dial clockwise to select next sub menu.

4
The service contract number is displayed¹. Turn the selection dial clockwise to select next sub menu.

5
The instrument serial number is displayed. Turn the selection dial clockwise to select next sub menu.

6
Instrument name and software version are displayed. Turn the selection dial clockwise to select next sub menu.

7
The date of the last service is displayed. Turn the selection dial clockwise to select next sub menu.

8
A test of the instrument buzzer is performed, press OK.

¹Not always pre-programmed. Depends on customer-specific contract.